Many applications of a wireless sensor network (hereinafter “WSN”) require the knowledge of where the individual nodes are located [1-3]. Yet robust sensor localization is still an open problem today. While there are many approaches in existence, they all have significant weaknesses that limit their applicability to real world problems. Techniques based on accurate ranging such as acoustic ranging have limited range [4-6]. They need an actuator/detector pair that adds to the cost and size of a platform. Furthermore, many applications require stealthy operation making ultrasound the only acoustic option. However, ultrasonic methods have even more limited range and directionality constraints [7, 8]. Methods utilizing the radio usually rely on a received signal strength that is relatively accurate in short ranges with extensive calibration, but imprecise beyond a few meters [8-10]. The simplest of methods deduce rough location information from radio hop count [11]. In effect, they also use radio signal strength, but they quantize it to a single bit. Finally, most of the proposed methods work in 2-demission (hereinafter “2D”) only. A recent survey of localization methods and their performance has been reported [8].
Existing WSN localization methods have either high accuracy or acceptable range, but not both at the same time. Furthermore, the very physical phenomenon they use—acoustics and radio signal strength—do not show any promise of achieving the significant improvement that is necessary to move beyond the current state of the art.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.